i have 04 rancher 4x4 i dont have but about fifteen hours on it i havent changed the oil yet. im goning to take it in for service next to change oil and adjust the valves. my brother has a 1986 honda foreman he bought it when it was one year old. its been rode hard but serviced regular. he changes his own oil and adjust the valves when needed. he has used nothing but castrol gtx in it since he bought it 20 w 50 in summer 10 w 40 in winter it runs as good today as it did when he bought it in 1987. the motor has not had any problems he has rebuilt the car two times. and new brakes and one shaft and that is it. almost 20 years old rode alot yeah i think castrol is pretty good thats what im going to use in my rancher.